The Trump administration said Thursday it would allow new offshore oil and gas drilling in nearly all United States coastal waters, giving energy companies access to leases off California for the first time in decades and opening more than a billion acres in the Arctic and along the Eastern Seaboard.

The proposal lifts a ban on such drilling imposed by President Barack Obama near the end of his term and would deal a serious blow to his environmental legacy. It would also signal that the Trump administration is not done unraveling environmental restrictions in an effort to promote energy production.

While the plan puts the administration squarely on the side of the energy industry and against environmental groups, it also puts the White House at odds with a number of coastal states that oppose offshore drilling. Some of those states are led by Republicans, like Gov. Rick Scott of Florida, where the tourism industry was hit hard by the Deepwater Horizon rig disaster in 2010 that killed 11 people and spilled millions of gallons of oil into the Gulf of Mexico.

Governor Scott vowed on Thursday to protect his state’s coast from drilling, saying he would raise the issue with Interior Secretary Ryan Zinke.

“I have asked to immediately meet with Secretary Zinke to discuss the concerns I have with this plan and the crucial need to remove Florida from consideration,” he said in a statement. “My top priority is to ensure that Florida’s natural resources are protected.”

The governors of New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, California, Oregon and Washington have all opposed offshore drilling plans. Virginia’s governor-elect, Ralph S. Northam, a Democrat, said in a statement Thursday that expanding drilling would jeopardize his state’s tourism and fishing industries, as well as military installations. Gov. Roy Cooper of North Carolina, also a Democrat, called drilling a “critical threat” to his state’s economy.

Mr. Zinke said the drilling plan was part of “a new path for energy dominance in America,” but said he planned to speak with Governor Scott and other state leaders before the proposal was finalized. “It’s not going to be done overnight,” he said.

Oil industry leaders cheered the reversal, calling it long overdue.

“I think the default should be that all of our offshore areas should be available,” said Thomas J. Pyle, president of the American Energy Alliance. “These are our lands. They’re taxpayer-owned and they should be made available.”

The Obama administration blocked drilling on about 94 percent of the outer continental shelf, the submerged offshore area between state coastal waters and the deep ocean. Mr. Zinke charged that those restrictions had cost the United States billions of dollars in lost revenue and said the new proposal would make about 90 percent of those waters available for leasing.

The Interior Department would open 25 of 26 regions of the outer continental shelf, leaving only the North Aleutian Basin — which President George H.W. Bush protected in an executive order — exempted from drilling.

Interior officials said they intended to hold 47 lease sales between 2019 and 2024, including 19 off the coast of Alaska and 12 in the Gulf of Mexico. Seven areas offered for new drilling would be in Pacific waters off California, where drilling has been off limits since a 1969 oil spill near Santa Barbara.

President Trump signed an executive order in April requiring the Interior Department to reconsider Mr. Obama’s five-year offshore drilling plan, which had invoked an obscure provision of a 1953 law, the Outer Continental Shelf Lands Act, to block new lease sales in large areas of the Arctic and Atlantic. The ban “deprives our country of potentially thousands and thousands of jobs and billions of dollars in wealth,” Mr. Trump said at the time.

Finalizing the new plan could take as long as 18 months, experts said, and in the meantime challenges are expected in the courts and in Congress.

In a joint statement, 64 environmental groups called the plan a “shameful giveaway” to oil companies. Many said they were exploring legal options.

Senator Edward J. Markey, Democrat of Massachusetts, vowed to pursue “all legislative tools” to block drilling off the East Coast, including the Congressional Review Act, which allows agency actions to be undone by Congress. Xavier Becerra, California’s attorney general, said the state is “evaluating all of our options” to protect its coast. And, several groups warned, a future Democratic administration could again redraw the boundaries of allowable drilling.

But for now, Republicans’ efforts to roll back restrictions on energy production are winning the day. Last month Congress opened the Arctic National Wildlife Refuge, or ANWR, to oil and gas drilling as part of the tax overhaul. And last week the Interior Department rescinded an Obama-era rule that would have added regulations for hydraulic fracturing, or fracking, on federal and tribal lands. It also repealed offshore drilling safety regulations that were put in place after the Deepwater Horizon spill.

Jody Freeman, director of the environmental law program at Harvard Law School and a former Obama climate adviser, said the latest Trump proposal was more about sending a message. In the Arctic in particular, she said, low oil prices and the decision by Royal Dutch Shell to give up all but one of its federal oil leases indicate drilling is not on the near horizon.

“But the decision is a signal, just like the one Congress sent with ANWR, that Republicans want to open the nation’s public lands and waters for business,” she said.

Frank Knapp, president of the Business Alliance for Protecting the Atlantic Coast, said thousands of small businesses, from restaurants to hotels to commercial fishing operations, oppose drilling off their states’ waters.

“It’s not consistent with our vibrant tourism, fishing and recreation,” Mr. Knapp said. “Their concern is their livelihood, the local economies. We all saw what happened to the Gulf Coast with Deepwater Horizon.”

Of particular interest to oil companies — and concern to many Florida lawmakers — will be the decision to open the eastern Gulf of Mexico, said Kevin Book, an energy consultant and managing director of ClearView Energy Partners. He noted the area is attractive to the energy industry because there is already a large amount of infrastructure in the region.

“You can talk about the Atlantic all you want, but you’re 10 years, 15 years from production,” Mr. Book said.

Analysts said the oil industry was unlikely to rush headlong into new areas. While oil companies have eyed regions like the East Coast for years, oil and gas operators are still smarting from the steep fall in oil prices that began in 2014 because of a global oil glut, which has only recently eased.

Despite the recent sharp rise in prices to about $68 a barrel for Brent crude, companies remain wary of spending, particularly in areas where the amount of oil and gas present is unknown and production is likely to be expensive without existing pipelines and other infrastructure.

“It is going to be a really long story,” said William Turner, an analyst at Wood Mackenzie in Houston. “It is not going to be gangbusters.”